The site cyclingva.com has a great list of events for the area and is my go to for finding them. The AFCC was one of my A events last year.
Re Skyline drive ride. There’s a supported event at the end of September that rides Skyline south on Friday, hotel overnight, and then returns northbound on Saturday. I have not done it but definitely have my eye on it.
There are great farm country roads just west of Manassas towards Nokesville. For climbs, Mt Weather is decent and you can stay on the ridge or dip down into Shenandoah Valley. You can pick up the W&OD trail from the Curtis Trail at the Pentagon and get 90-100 miles round trip.
I live in Manassas and work at the Navy Yard. This is my eighth year here across two sets of orders. Previously I lived in West Springfield. Feel free to PM me with any questions on the area or moving here on orders.
Also, Conte’s downtown and Green Lizard in Herndon are good LBS’s.